Flexible skin package

ABSTRACT

A moisture and oil impervious package formed by a type of skin packaging technique. The present invention is characterized by elimination of the paper board backing sheet of the prior art and employs a plastic drape sheet and a high density ionic copolymer base sheet.

United States Patent Smith 14 1 Apr. 11, 1972 [541 FLEXIBLE SKIN PACKAGE 3,261,538 7/1966 Jones et a1 ..229/87 F 2 813 799 11/1957 Bender et a1 ..206/56 AA 72 Inventor: Bar A. Smith Ballfall Road, l 1 Midgemwm Com 06457 2,589,604 3/1952 Cunningham et a] ..206/62 3,468,412 9/1969 Forman ..206/46 R [22] F 30, 1969 3,137,387 6/1964 Overment ..206/63.2 R [21] Appl 9,35 3,024,579 3/1962 Stockhausen et a1. ..206/80 A Related Applicaflml Data Primary Examiner-William T. Dixson, Jr. [63] Continuation-impart 0f Ser. N0. 816,306, Apr. 15, Attorney-FEM and Van Kirk 1969, abandoned.

[57 ABSTRACT 52 us. c1 ..53/22, 206/46 FR, A moisture CM 0 impervious package formed by a type of 511 1111.01. ..B65d 73/00, B65d81/14, 865d 85/58 Packagmg technique' The is [58] Field 61 Search ..206/80 A, 56 AA, 46 R, 46 FR, terized by elimination of the P p board backing Sheet of the 206/46 H, 4 pv 2; 229 7 R, 37 P; 53/30 prior art and employs a plastic drape sheet and a high density ionic copolymer base sheet. c166 [56] References I 4 Claims, 3 Drawing Figures UNITED STATES PATENTS 3,154,898 11/1964 Eng1es,.1r ..206/80A FIG.1

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F/SHMA/V 5 WW KIRK ATTORNEYS PATENTEDAPR 11 I972 3, 654, 744

sum 2 OF 2 BACKING SHEET PRESERVE ARTICLE 7 :2 1 cuT TOYSIZE PLACE ARTICLE ON 16/ BACKING a INSERT IN MACHINE INSERT DRAPE SHEET IN CLAMP FRAME DROP CLAMP FRAME WHILE HEATING AFTER HEAT 24% RETRACT HEATER SEPARATE 3i FOLD 8 BOX INVENTOR HARRY A. SMITH F/SHMAA/ 8 VAN KIRK ATTORNEYS FLEXIBLE SKIN PACKAGE CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-impart of co-pending application serial number 816,306, filed Apr. 15, 1969 now abandoned.

BACKGROUND OF THE INVENTION:

1. Field of the Invention The present invention relates to packaging. More particularly, the present invention is directed to air, oil and moisture impervious skin packages. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.

2. Description of the Prior Art While not limited thereto in its utility, the present invention is particularly well suited to the packaging of relatively heavy articles. Thus, the present invention has been successfully employed in the packaging of bearings. Packages for shipping replacement bearings, particularly those which comply with military specifications, have very stringent requirements. The package must be hermetically sealed in order to prevent exposure of the contents to moisture. Also, since bearings are typically coated with a preservative prior to packaging, the package must be impervious to the preservative. It is also desirable to have at least one, and often both, sides of the package transparent so that the contents thereof may be visually inspected. Further, it is desirable that the package provide a measure of cushioning so as to protect the contents from marring and brinelling. Finally, the design of the package, while immobilizing the contents, must also enable removal of the contents without scratching or other damage.

Continuing with a consideration of packages particularly well suited for items such as bearings, only those in accordance with the technique disclosed in U.S. Pat. No.

3,024,579, issued to C. J. Stockhausen et al. on Mar. 13, 1962 have previously received military approval. As will be obvious to those skilled in the art, the multistep packaging technique of Stockhausen et al, especially in view of the use of an adhesive and the necessity to invert and trim the package as an intermediate step in the process, is quite time-consuming and thus expensive. Accordingly, a desire has existed for a method of packaging wherein the resulting container would have the desirable attributes of the Stockhausen et al. package but the packaging could be performed in a more expeditious manner.

There have, of course, been other attempts at producing hermetically sealed packages which depart from the approach of above-mentioned Stockhausen et al. U.S. Pat. No. 3,024,5 79. These alternate approaches have typically employed conventional skin packaging technology wherein the article to be packaged was placed on an air pervious backing sheet, usually paper board, and was covered with the plastic drape sheet in the actual packaging step wherein the sheet was heated while a vacuum simultaneously drawn. In order to provide hermetic sealing, the surface of the backing sheet directly beneath the article to be packaged was rendered air impervious. An example of this approach may be found in U.S. Pat. No. 3,358,829, issued to H. A Smith et al. on Dec. 19, 1967. In accordance with the Smith et al. patent, the article was hermetically sealed by forming a fusion bond between the drape or cover sheet and both the backing board and a second sheet of plastic material which was bonded thereto, the article to be packaged being positioned on the second sheet. Although attractive for many applications, the packaging technique of the Smith et al. patent nevertheless requires an additional step of positioning the second or barrier sheet on the backing board prior to the actual skin packaging operation and does not result in a flexible package.

It is to be noted that attempts have been made to provide hermetically sealed packages by employing partially or totally coated backing boards. Use of coated boards has, however, not proven particularly successful, especially for heavy articles, due to an inability to obtain at least partial encapsulation of the article to be packaged. As will be obvious to those skilled in the art, substantial immobilization of an article such as a bearing is necessary in order to prevent rupture of the drape sheet during later handling, and such immobilization can be practically achieved only through partial encapsulation.

SUMMARY OF THE INVENTION:

The present invention overcomes the above-discussed and other problems and disadvantages of the prior art and in so doing comprises a novel and improved package and method of forming the same. In accordance with this invention, the article to be packaged is positioned on a base sheet comprised of a flexible, high density, fusible, plastic material. Thereafter, a drape sheet which will bond to the base sheet when heated is deposited over the article and base sheet. In a departure from conventional skin packaging techniques no backing board is employed with the present invention. Also in contradistinction to the prior art, the present invention does not utilize a preheat step and the drape and base sheets are heated simultaneously as the drape sheet supporting clamp frame descends in the packaging machine. When the frame reaches its lower limit of movement and the drape sheet contacts the upper surface of article being packaged and the base sheet, a vacuum will be drawn while heating continues. During this after heat step, the space under the drape sheet will be partly evacuated, causing the drape sheet to partly conform to the contour of the article, and the drape sheet will be fusion bonded to the base. As a result of proper selection and control of the process parameters and-proper selection of base sheet size, the article will thus be partly encapsulated while simultaneously being herrnetrically sealed. The packaged article may now be removed from the packaging machine, cooled and the four corners of the flexible base sheet folded over to provide a cushion which wraps entirely around the article.

BRIEF DESCRIPTION OF THE DRAWING:

The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawing wherein like reference numerals refer to like elements in the several figures and in which:

FIG. 1 is a cross-sectional, side elevation view of a portion of a first embodiment of a package in accordance with the present invention.

FIG. 2 is a perspective view of a completed package in accordance with the embodiment of FIG. 1.

FIG. 3 is a flow diagram depicting the various steps performed in practice of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

In accordance with the present invention, since it is generally considered desirable to employ the full capacity of the packaging machine to thereby simultaneously package a plurality of articles, modular size backing sheets are selected. Thus, as indicated in step 10 of FIG. 3, the backing sheet material is selected. Thereafter, as indicated in step 12, the backing sheet material is cut into pieces, typically of square shape, of the proper modular size.

A particularly novel feature of the present invention is the selection, for the backing sheet material, of an ionomer which is flexible and air, moisture and oil impervious. In the practice of a first embodiment of the present invention it has been found desirable to employ, as the backing sheet, a closed cell plastic material having a density in excess of six pounds per cubic foot. Particularly good results have been achieved by employing a material known as Softlite 10" available from the Gilman Brothers Company, Gilman, Connecticut and comprising a Surlyn-A ionic copolymer produced by E. I. du Pont de Nemours & Company. The raw material provided by du Pont is foamed by Gilman Brothers Company to provide material in sheet foam and having the desired density. Al-

ternately, and in accordance with a second embodiment of the invention, the Surlyn A may be employed in film (unfcamed) form. In film form, the material has a density of approximately 20 pounds per cubic foot.

While not always necessary or desirable, it is usually considered advantageous to select the backing sheet size so that the corners of the package may be folded over, as shown in FIG. 2, thereby cushioning the article being packaged on all sides. Thus, if a cushioned bearing package is to be produced as shown in FIG. 2, a square backing sheet having a width of 1.4 X (diameter of bearing height of bearing one-fourth inch) is employed; the results of any calculation being rounded off to the nearest one-half inch.

As indicated in step 14, either after preparation of the backing sheets or simultaneously therewith, the articles to be packaged are cleaned and preserved. Typically, the preservation step contemplates the dipping of the articles in a preservative. In the case of bearings, the articles are dipped in oil and, as indicated in step 16, individually centered on modular backing sheets which are thereafter placed on the bed of the packaging machine. It is to be noted that when a plurality of individual packages are to be formed simultaneously space must be left between each of the backing sheets placed on the machine bed whereby a vacuum may be drawn around each backing sheet. It is also to be noted that it is possible to package a plurality of articles on a single backing sheet but this would not be done where the articles are relatively heavy or where sudden contact between the articles might cause damage. While any commercially available skin packaging machine may be employed in the practice of the present invention, tests have been conducted on an Ampak machine having a 36-by-36-inch bed.

As shown at step 18, the next step in accordance with the present invention comprises the selection of a suitable drape sheet and the installation of that sheet in the clamp frame of the packaging machine. A requirement for the drape sheet material is that it be compatible with the base sheet material whereby it may be caused to fusion bond thereto to produce a hermetic seal without the use of any adhesive. Tests with a Softlite l" closed cell, foamed plastic base wherein a 20-mil thickness Surlyn-A plastic film was employed for the drape sheet have been extremely successful. Successful tests have also been performed using transparent 20-mil Surlyn-A plastic film for both the base and drape sheets. The only substantial advantage of using a film base sheet is that it permits visual inspection from both sides of the completed package. The size of the drape sheet will, of course, be determined by the dimensions of the machine and typically a single drape sheet will be employed to package several articles resting on separate backing sheets in a single operation.

After the drape sheet has been installed in the clamp frame of the skin packaging machine, the packaging cycle will be instituted. It is to be particularly noted that, contrary to the prior art, packaging in accordance with the present invention does not employ a substantial preheating step wherein the drape sheet would be heated prior to the time that the clamp frame of the machine begins to move vertically downward. In the prior art, it is conventional practice to preheat for one second for each mil of thickness of the drape sheet. Thus, in accordance with the present invention, again considering the example of the pound per cubic foot density foamed base and a 20-mil drape sheet, the machine heaters will be set to provide approximately l,000 F. and the clamp frame will be dropped as soon as the heater comes on (no preheat) to thereby simultaneously heat the drape sheet and backing sheet; as indicated at step 20 in FIG. 3. In the case of the 20- mil film base and drape sheets, similarly no preheat cycle was employed.

When the clamp frame of the machine descends to the point where it hits the machine bed, the rate of descent of the frame being a function of the machine and not controllable, the vacuum pumps beneath the machine bed will be automatically energized as indicated at step 22. Step 22 is known in the art as the after heat" or postheat" step wherein a vacuum is pulled while the application of heat is continued. In the example being discussed, wherein a 10 pound per cubic foot density foamed backing sheet and a 20-mil drape sheet both comprised of Surlyn-A" are employed, the vacuum will be pulled for approximately 30 seconds, the vacuum pumps pulling approximately 22 inches of mercury, without adjusting the heat setting of 1,000" F. In the film-film example, the after heat time was 35 seconds.

As indicated at step 24 in FIG. 3, at the termination of the after heat step, the heater will be retracted and the resulting packages will be cooled as noted at step 26. Next, since the several packages formed will be interconnected by means of the drape sheet, the drape sheet will be cut (in step 28) in the regions where spacing was left between the backing sheets on the machine bed to thereby separate the various individually packaged articles. Finally, in cases where a backing sheet of sufficient size to permit a fully cushioned package is employed, the packaging willbe completed in step 31 by folding over the corners of the backing sheet and placing the package in a box. It is to be noted that the folded over edges of the package will take a permanent set after a few hours in a box and, if desired, the packaged articles may thereupon be moved from their individual cartons and several articles packaged in a single carton.

The article resulting from performance of the process discussed above, is shown in FIGS. 1 and 2. In FIGS. 1 and 2, a closed cell, foamed plastic base sheet is indicated at 40 while the plastic film drape sheet is indicated at 42. A bearing which has been packaged in accordance with the present is schematically illustrated at 44 in FIGS. 1 and 2. FIGS. 1 and 2 clearly show the partial encapsulation of the article 44 by the drape sheet 42 achieved through use of the present invention. If the conventional preheating step of the prior art is employed, the film 42 will immediately bond to the base sheet 44 thereby preventing the drawing of air from between the two sheets of material, as accomplished in after heat step 22, whereby the heat-softened drape sheet will be drawn down and will at least partly conform to the shape of the article 44 being packaged. As previously noted, for relatively heavy articles encapsulation is necessary to immobilize the article. FIG. 2 depicts the completed package with three corners of the square backing sheet 40 turned over the article to provide a cushion. In FIG. 1, reference numeral 46 indicates the oil preservative for the bearing 44; the quantity of oil shown being that of a test package and much greater than employed in actual packaging.

To summarize the desirable features and/or improvements precipitated by the present invention, it is to be noted that a substantially single-step skin packaging technique which results in a flexible, air, water, oil and dust impervious package is provided. Since the present invention is essentially a single-step packaging process, there are substantial savings in manufacturing costs over the prior art. The present invention also provides vastly superior shock protection than available in the prior art. Further, the present invention, as a result of the fillet formed around the base of the article, provides a package from which the article may be removed without any danger of marring. In prior art bearing packages, as exemplified by the aforementioned Stockhausen et al. patent, it was necessary to carefully cut the plastic material from the article and damage to the bearings often resulted. Similarly, in accordance with the present invention, there is practically no possibility of contamination of the article by pieces of packaging material which are either not removed or which fall into the interior of the article during the trimming operation previously required.

While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the present invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

What is claimed is:

1. A packaging process comprising the steps of:

forming modular size backing sheets from a flexible, oil impervious, plastic material having a density in excess of 6 pounds per cubic foot;

placing articles to be packaged on the modular backing sheets on the bed of a skin packaging machine;

depositing a plastic drape sheet over the articles and backing sheets, the drape sheet being capable of being fusion bonded to the base sheet by the application of heat and without the use of an adhesive;

simultaneously heating the base sheets and drape sheet; and

partly evacuating the region between the drape and base sheets whereby the heat softened drape sheet will partly encapsulate the articles.

2. The process of claim 1 wherein the step of depositing the drape sheet includes applying heat to the drape sheet and base sheets.

3. The process of claim 2 further comprising the steps of cooling the drape sheet and backing sheets;

cutting the drape sheet to separate a plurality of articles packaged on the modular base sheets; and folding the comers of the individual packages over the articles whereby the articles will be cushioned on all sides by the base sheet material. 4. The process of claim 1 further comprising: coating the articles to be packaged-with a liquid preservative prior to placement on the modular backing sheets.

i 1! i I. i 

1. A packaging process comprising the steps of: forming modular size backing sheets from a flexible, oil impervious, plastic material having a density in excess of 6 pounds per cubic foot; placing articles to be packaged on the modular backing sheets on the bed of a skin packaging machine; depositing a plastic drape sheet over the articles and backing sheets, the drape sheet being capable of being fusion bonded to the base sheet by the application of heat and without the use of an adhesive; simultaneously heating the base sheets and drape sheet; and partly evacuating the region between the drape and base sheets whereby the heat softened drape sheet will partly encapsulate the articles.
 2. The process of claim 1 wherein the step of depositing the drape sheet includes applying heat to the drape sheet and base sheets.
 3. The process of claim 2 further comprising the steps of cooling the drape sheet and backing sheets; cutting the drape sheet to separate a plurality of articles packaged on the modular base sheets; and folding the corners of the individual packages over the articles whereby the articles will be cushioned on all sides by the base sheet material.
 4. The process of claim 1 further comprising: coating the articles to be packaged with a liquid preservative prior to placement on the modular backing sheets. 